Rectifying apparatus and method of making



June 17, 1930. H G ANDRE 1,764,770

RECTIFYING APPARATUS AND METHOD OF MAKING Filed 001:. 29, 1926 PatentedJune 17, 1930 UNITED STATES;

HENRI G. ANDRE, OF PARIS, FRANCE RECTIFYINGtAPPARAT'lTS AND METHOD OFMAKING Application filed October 29, 1926. Serial No. 145,017.

The present invention relates to electrical apparatus and in particularto alternating current rectifiers in which two metals of differentcharacter are employed as electrodes, the metals fulfilling alternatelythefunction of cathode and anode.

In my application Serial No. 7 49,214, filed November 11, 1924, entitledUnilateral conductor for rectifying alternating current, I

have dis-closed a rectifier, one electrode of which comprises a metalliccolloid while the other is formed of a material that, when subjected-toan oxidizing agent, yields a surface layer of such nature that thedevice is perme- 1 able to current in one direction only In theapplication supra the compound was derived by surrounding the electrodeswith acid and passing an electric current between them.

In accordance with the above identified application, the colloid ispreferably silver,

the oxidizing liquids being sulphuric acid and water vapor'absorbingmaterials, such as meta-phos horic acid, while calcium chloride may healso employed as a water vapor absorber. Ortho-phosphoric may also beused as an oxidizer.

Now, I have found that the resistance of the rectifier may beconsiderably reduced by the application of pressure to the colloid.

acid

' In order to prevent a possible short circuit due to intensity ofpressure offered by the metallic particles to the surface of the otherelectrode, I propose to increase the thickness of oxide layer on thelatter. .Briefly, this is accomplished by treating the electrode priorto immersion in the aci The primary object of m invention is to reducethe internal losses 0 the colloid type of rectifier so called, andanother object is to simplify the mode of manufacture, A still furtherobject is to improve the unilaterally conducting characteristic-of suchrectifier. Other features'will be apparent as the specification isperused.

The accompanying drawing illustrates an exemplary embodiment of thedevice forming the subject of the present invention.

The figure shows a vertical section: of the improved rectifier. 1Referring to the illustration, the invention in its preferred formconsists of a tube or receptacle 1 having an enameled interior and madeof a metal passive to concentrated acid, for example, iron. One end ofthe receptacle is closed by the material forming the tube and the otherby an amorphous sealing compound 2 of sulfur or the like. At the bottomthere is located electrode 3, hereinafter referred to as anode, of ametal,'as silver, which lends itself readily to colloidal form andhaving oxidation products that are relatively good. conductors ofelectrical ener This electrode is of such thickness as to be readilysecured to latter by rivet 4, preferably of the sprung to the form ofthe receptacle, being same material as the anode. A snug fit between thesilver member and casing prevents deleterious effects caused byelectrolyticac tion at the joint and also about the periphery of \therivet. By the'numeral 5 I designate a quantity of metal in powdered formof the same material as the anode and derived by well-known processes,filling the space below the level indicated by dash and dot line whiledirectly above, there is a mass of liquid absorbing material 6 as sand,glass wool or the like, supporting layer 7 of asbestos. By horizontallines 8 the presence of acid in concentrated form is denoted, completelysatur ating the absorbing material.

In order to prevent creepage of liquid by capillarity, I provide glassring 9 separating asbestos layer 10 from the one adjacent Centrallydisposed of the structure and sunk to considerable depth in the powderedmetal, is another electrode 12, hereinafter referred to as cathode,of analloy, as nickel-silicon, the surface of which is rendered permeable tocurrent in one direction only. As stated, the entire structure is heldin place by the sulfur covering into which indentations 11 of the casingare made. .These indentations I support circular plate 13 of insulatingmaterial, as vulcanite, ebonite, in the center of which is locatedmetallic thimble 14. The latter is connectedjto member 12 by lead 15 Vof a material similar to the cathode, the

thimble having dimensions suitable for pressmg into a standard clipcontact. It is ob- VlOllS, however, that the device mayterminate inother forms of structure for convenience in making electrical connectionto external circuits. Apparatus made according to the foregoingspecification has the property of rectifying alternating current ofcomparatively large amplitude.

In the manufacture of my device procedure is as follows: The anode isfirst secured to the casing and the required amount ofpowdered silverheaped thereon. Cathode 12 is heated by external means, as in a furnace,to a red color, approximately 500 0., and in this condition tightlypressed into the cen' ter'of the silver mass tending to com ress theparticles in the neighborhood 0 the cathode. This in turn has thedesirable effect of decreasing the internal resistance of the rectifier,and consequent losses. While pressure on the cathode is continued, asmall quantit of silver is added, the upper surface 0 which supports thesand or glass wool; acid is then poured until the absorbing materialbecomes saturated. U on contact with, the acid the heated .catho 0causes violent sputtering and a heavy oxide layer is formed whichadheres tenaciously to the metal imparting to the rectifier a long lifeof stable operation and also precluding any possibility of short circuitdue to pressure exerted by the silver particles. The asbestos platesseparated by the glass rin are inserted next resting on the mass of santhe sulfur seal being then poured and finally, the

insulating cap and thimble added.

It is apparent that, if desired, the function of either cathode or anodecould be transferred to the container in which case, the latter wouldcomprise nickel-silicon or silver, respectively.

I claim:

1. In a rectifier of the type havin two spaced electrodes with a mass offine y divided conducting material substantially bridging the spacetherebetween and one of 'the electrodes of which contains an oxidationproduct derived from a surrounding acid, the method which consists inheating the latter electrode prior to subjection to acid to increase thethickness of layer and applying pressure to increase the intensity ofsurfacial contact with the finely divided material.

2. In a rectifier the combination of a receptacle one end of which isclosed by a stopper, an anode in sub-divided form, a cathode associatedtherewith means including a liquid operating in con] unction with saidanode and cathode to cause unidirectional flow of current, and means forsubstantially reventing passage'of the liquid to that en of thereceptacle containingthe stopper, all of said elements being located insaid receptacle.

, 3. In a rectifier, a receptacle containing the following incombination, an anode in with the anode and cathode to cause unidirectional flow of current.

4. Asan article of manufacture, a receptacle the material of whichcloses one end, containing two electrodes immersed in acid means forabsorbing superfluous liquid and having superimposed thereon a pluralityof layers of asbestos separated by a glass member to prevent creepagealong the walls of the receptacle and an amorphous compound closing theopen end of the latter.

5. A rectifier comprisin a cup sha ed container and anodic mass in nelydivi ed form at the bottom thereof, said anodic mass having a corrosiveliquid therein, a member connecting said anodic mass with the outside ofsaid container, a cathode centrally disposed of the container and havinga rtion buried in the anodic mass, a layer 0 liquid absorbing materialabove said anodic mass, two layers of li uid absorbing material anddifferent from t e first layer, means including a glass member forspacing said two layers of absorbing material. whereby creepage ofliquid is prevented and means for sealing the top of said container.

Signed by me at Boston, Massachusetts, this 17th day of September, 1926.

HENRI G. ANDRE.

subdivided form, the particles of which are. I

